Battery casing and sealed primary sodium-halogen battery

ABSTRACT

A battery casing and a sealed primary sodium-halogen battery are disclosed wherein the battery casing includes a single seal of low temperature melting glass joining together the metallic anode cap, the inner casing of a solid sodium ion-conductive material, and the outer metallic casing. A sealed primary sodium-halogen battery has the above type of casing with a sodium anode in one casing and a cathode of a halogen in conductive material in the other casing.

Ill] 3,918,992

[ Nov. 11, I975 United States Patent on Will et al.

[22] Filed:

rillulllt). Agent, or Firm-Paul R. Webb ll; Joseph T. Cohen; Jerome CSquillaro [Zll Appl. No.:

[57] ABSTRACT A battery casing and a sealed primary sodium-halogenhatter) are disclosed wherein the battery casing in- Ih. I973. Pat. No.

cludes a single seal of low temperature melting glass joining togetherthe metallic anode cap. the inner cas- 606 606 il /ll on U A 6 6 U0 U0 o70 .1 M1,. Z m R m6 3 WU 8H i. 6 U 3 NH I. H M in NC H l m l M s uw UIFH M 555 ing ofa solid sodium ion-conductive material. and the outermetallic casing, A sealed primary sodium- [56] References Cited UNITEDSTATES PATENTS halogen battery has the above type of easing with asodium anode in one casing and a cathode of a halogen in conductivematerial in the other casing.

2 Claims, 2 Drawing Figures Christopher Christopher t Zf ZzZ JIAAI/XZIAZ/AZ AZZ 1/ BATTERY CASING AND SEALED PRIMARY SODIUM-HALOGENBATTERY and to sealed primary batteries and, more particularly,

to such battery casings and to sealed primary sodiumhalogen batteries.

Sodium-sulfur cells, which operate at elevated temperatures, are knownin the prior art as, for example, described in Kummer et al U.S. Pat.No. 3,404,036 issued Oct. l. i968 under the title Energy ConversionDevice Comprising a Solid Crystalline Electrolyte and a Solid ReactionZone Separator." The solid crystalline ion-conductive electrolyte in theabove-mentioned sodium sulfur battery can be sodium beta-alumina.

A sealed primary sodium-halogen battery is known in the prior art as,for example, described in Dubin U.S. Pat. No. 3,762,955 issued Oct. 2,I973, under the title Sealed Primary Sodium-Halogen Battery. This patentis assigned to the same assignee as the present application. This patentdescribes and claims such a battery with a specific outer glassenvelope.

ln copending patent application Ser. No. 230,864, filed Mar. l, 1972 nowabandoned, entitled Battery Casing and Sealed Primary Sodium-HalogenBattery" in the names of Heinrich .l. Hess and Fritz G. Will, there isdescribed and claimed a battery casing and a sealed primarysodium-bromine battery in which a low temperature melting glass sealsthe flat cover, the flange of the outer casing, and the upper surface ofthe inner casing together.

In copending U.S. Pat. application Ser. No. 239,890, filed Mar. 31, i972now U.S. Pat. No. 3,826,685, in the names of Robert R. Dubin et al andentitled Wall Sealed Battery Casing and Sealed Primary sodium- HalogenBattery," there is described and claimed a battery casing and a sealedprimary sodium-halogen battery in which a sodium and halogen resistantglass seals together the adjacent flanges of the outer vessel portionsand seals the outer vessel portions to the outer wall of the innervessel. Both of the above copending patent applications are assigned tothe same assignee as the present application.

Our present invention is directed to providing an improved batterycasing and an improved sealed primary sodium-halogen battery over theabove-identified patent and patent applications in that a single lowtemperature melting glass seal seals together the adjacent flanges ofthe upper portion of the outer metallic casing and the anode cap, andseals the flanges to the outer wall of the inner casing adjacent itsopen end.

The primary objects of our invention are to provide an improved batterycasing and an improved low temperature primary battery which has a zeroself-discharge rate, high cell voltage and high energy density.

ln accordance with one aspect of our invention, a battery casingincludes a single seal of low temperature melting case which joinstogether the metallic anode cap, the inner casing ofa sodiumion-conductive material, and the outer metallic casing adjacent the openend of the inner casing.

These and various other objects, features and advantages of theinvention will be better understood from 2 the following descriptiontaken in connection with the accompanying drawing in which:

FIG. 1 is a sectional view ofa battery casing made in accordance withour invention; and

FIG. 2 is a sectional view of a battery made in accordance with ourinvention.

In FIG. 1 of the drawing, there is shown generally at 10 a batterycasing embodying our invention which has an inner casing of a solidsodium ion-conductive material 11 with one open end 12. An outermetallic casing 13 has an upper portion 14 and a lower portion 15. Upperportion 14 has opposite open ends 16 and 17. An inwardly extendingflange 18 is affixed to upper portion 14 at its first open end 16 and aflare 19 at its open end 17. Lower portion 15 has an open end 20, anopening 21 and a removable closed end 22. Upper and lower portions 14and 15 are joined together as by welding at 23 at their associated openends 17 and 20. Outer metallic casing 13 surrounds inner casing 11 withexterior surface 24 of flange 18 on a lower plane than surface 25 atopen end 12 of inner casing 11 and spaced from inner casing l l. A cap26 with a flange 26' is positioned adjacent to and spaced from flange18. A single low temperature melting glass seal 27 seals together flange18 of upper portion 14 of metallic casing 13 and flange 26' of cap 26and seals flanges 18 and 26 to outer wall 28 of inner casing 11 adjacentits open end 12.

In FIG. 2 of the drawing, there is shown a sealed primary sodium-halogenbattery 30 embodying our invention which battery includes theabove-described battery casing shown in FIG. 1. An anode 31 ispositioned preferably in inner casing 11. Anode 31 which is shown assodium metal, is selected from the class consisting of sodium, sodium asan amalgam, or sodium in a nonaqueous electrolyte. A cathode 32 of ahalogen in conductive material is positioned preferably within outercasing 13 and in contact with outer wall 28 ofinner casings 11 and withthe inner wall of casing 13. An electronic conductor 33 is positionedwithin inner casing 11 and extends outwardly through open end 12 ofinner casing 11. A metallic closure consists of cap 26 with flange 26'and a cap insert 35. Cap insert 35 is positioned within cap 26 andwelded thereto at 36 to seal open end 12 of inner vessel 11. Electronicconductor 31 is shown welded to the interior surface of closure portion35. A fill tube 37 is shown affixed to closed end 22 by means of weldingflange 38 thereto. The opposite end of the fill tube is closed at 39,for example, by welding. The resulting structure is a sealedprimary-halogen battery embodying our invention.

We found that we could form a battery casing by positioning an innercasing of a solid sodium ionconductive material having an open endwithin an outer casing of a suitable, chemically stable material such asa metal of niobium or tantalum which comprises an upper portion and alower portion, the upper portion with opposite open ends, an inwardlyextending flange affixed to the upper portion at its first open end, thelower portion with opposite open ends, a removable closed end for itsfirst open end, with an opening in the removable closed end, and theupper and lower portions joined together at their associated second openends, such as by welding. The outer metallic casing surrounds the innercasing with the exterior surface of the flange on a lower plane than thesurface of the open end of the inner casing and spaced from the innercasing. A cap with a flange is positioned adjacent the flange of theupper portion of the outer metallic casing. A single low temperaturemelting glass in the form of a washer is positioned between the adjacentflanges and in contact with the exterior wall of the inner vessel. Theglass washer which melts at a low temperature is made of a suitablesodium and halogen resistant glass, such as Corning Glass No. 7056,General Electric Company Glass No. I013, Sovirel Glass No. 747, orKimble Glass No. N- 51A. The glass washer and associated assembly isthen heated to a temperature in the range of 1,l75 to 1,250C in an argonatmosphere whereby the glass seals together the flange of the upperportion of the outer metallic casing and the cap flange and seals theflanges to the outer wall of the inner vessel adjacent its open end.This structure results in a battery casing made in accordance with ourinvention.

We found that we could form a sealed primary sodium-halogen battery byemploying the above-described battery casing. The anode may consist ofsodium, a sodium amalgam or sodium in a nonaqueous electrolyte. Theanode is positioned preferably within the inner casing. When the sodiumis in the form of a sodium amalgam its range of compositions is fromabout 95% sodium and 5% mercury by weight to about 35% sodium and 65%mercury. For the fully charged state of the cell. the amalgamcomposition is preferably high in sodium. Cells using sodium amalgamcannot be used efficiently at temperatures below 21.5C due to completefreezing of the amalgam.

The use of nonaqueous electrolytes permits battery operation to muchlower temperatures as determined by the freezing point of the nonaqueouselectrolyte. The preferred electrolyte is propylene carbonate in which asodium halide salt is dissolved. This electrolyte permits batteryoperation down to -48C.

The cathode is positioned preferably within the metallic casing throughthe associated fill tube and is in contact with both casings. Thecathode comprises a mixture of bromine and iodine with from 5 to 60weight percent iodine in electronically conductive material and withdissolved small amounts of additives. The electrically conductivematerials for the mixture of bromine and iodine include a porous matrixof carbon felt, and a porous matrix of foam metal. The dissolvedadditives are sodium bromide, or sodium bromide and water. Small amountsof these materials are approximately 0.5 percent by weight. As it willbe appreciated, the anode and cathode electrodes can be positioned inthe opposite casings of the battery. in the preferred method of forminga sealed primary sodium-halogen battery, we form the battery casing asdescribed above and shown generally in FIG. 1, except that the lowerportion of the outer metallic casing is not joined initially at its openend to the open end of the upper portion of the same casing. An amountof mercury is placed within the inner vessel. The amount of mercuryemployed is the amount required in the sodium amal gam to be used as theanode. The insert of the closure with attached electronic conductorextends within the interior of the inner casing and contacts the mercurytherein, and the insert fits within the cap of the closure and is weldedthereto. In this manner, the insert seals the open end of the innercasing. The inner casing is then filled with sodium to provide a sodiumamalgam anode. This is accomplished in accordance with the methoddescribed and claimed in U.S. Pat. No. 3,740,206 issued June 19, 1973.This patent is assigned to the same assignee as the present application.

It will, of course, be appreciated that the sodium, for example, in theform of sodium amalgam can be added directly to the interior of theinner casing before the insert is positioned and sealed to the cap.Further, other manners of filling the inner casing with a sodium typeanode can be employed. A suitable method is to provide a fill opening orfill tube in the insert through which the inner casing is filled withthe sodium type anode.

ln the preferred method, the second open ends of the upper and lowerportions of the outer metallic casing are welded together. Conductivematerial is then positioned around and in contact with the exteriorsurface of the inner casing. For example, carbon felt in the form ofwashers are slipped around the exterior surface of the inner casing. Theremovable closed end is then positioned in the first open end of thelower portion. The removable closed end is welded to the lower portion.A mixture of bromine and iodine with from 5 to 60 weight percent iodinewith dissolved small amounts of additives is added through the fill holeor fill tube in the outer casing thereby providing a cathode within andin contact with the outer casing and in contact with the exteriorsurface of the inner casing. The fill hole or fill tube is then closed,for example, by welding. The resulting structure is a sealed primarysodium-halogen battery made in accordance withour invention.

Examples of battery casings and sealed primary sodium-halogen batteriesmade in accordance with our invention are set forth below:

EXAMPLE 1 A battery casing was assembled as above described and as shownin FlG. l by positioning an inner casing of a solid sodiumion-conductive material with one end partially within the upper portionof an outer tantalum metallic casing with opposite open ends and aninwardly extending flange affixed to the upper portion at its first openend. A tantalum cap with a flange was positioned so that the cap flangewas adjacent the flange of the upper portion. A single low temperaturemelting glass seal was provided initially by positioning a glass washerof Kimble Glass No. N-51A, which is sodium and halogen resistant,between the flanges and in contact with the exterior surface of theinner casing. The associated flanges and glass washer were aligned sothat the outer surface of the flange of the outer metallic casing was ona lower plane than the surface of the open end of the inner casing andspaced from the inner casing. The assembly was then heated in an argonatmosphere at a temperature of l,lC whereby the glass washer provided asingle glass seal sealing together the adjacent flanges and sealing theflanges to the outer wall of the inner casing adjacent to but spacedfrom its open end. The lower portion of the tantalum outer metalliccasing had opposite open ends, a removable closed end. and an opening inthe removable closed end. The upper and lower portions of the outermetallic casing were then joined together at their associated first openends by welding. The removable closed end was positioned in the firstopen end of the lower portion. This structure resulted in a batterycasing made in accordance with our invention.

EXAMPLE ll A sealed primary sodium-halogen battery was assembled asabove described and as shown in FIG. 2. The

battery casing was assembled as described above in Example 1 except thatthe lower portion of the outer casing was not welded to its upperportion. An insert of tantalum which forms part of the closure hadattached thereto by welding on its interior surface an electronicconductor in the form of a mil thick tantalum wire formed into a loop.0.62 g of mercury were placed within the inner casing to subsequentlyprovide a sodium amalgam as the anode. The insert was then fitted withinthe cap whereby the electronic conductor extended within the innercasing, contacted the side wall, and the mercury therein. The insertsealed the open end of the inner casing. The insert was then welded tothe cap under high vacuum of 5 X l0 torr. The interior casing was thenfilled with sodium to provide a sodium amalgam anode within the interiorcasing. This was accomplished generally in accordance with the methoddescribed and claimed in the above described US. Pat. No. 3,740,206. Thesecond open ends of the upper and lower portions of the outer metalliccasing were then welded together. Carbon felt in the form of a pluralityof washers were slipped around the exterior surface of the interiorcasing. The removable closed end is then positioned in the first openend of the lower portion. The removable closed end was welded to thelower portion. A mixture of 89.0 weight percent bromine, 10.0 weightpercent iodine, 0.5 weight percent water, and 0.5 weight percent sodiumbromide was added through the fill hole in the closed end of the outerportion of the casing by means of a syringe. In this manner there wasthen provided a cathode within and in contact with the outer casing andin contact with the exterior surface of the interior casing. The fillhole was then closed by welding. The resulting structure was a sealedprimary sodium-halogen battery made in accordance with our invention.

EXAMPLE Ill At room temperature, the sealed primary sodiumhalogenbattery of Example [I exhibited the following polarization behaviorwhich is shown in Table l.

TABLE 1 Current Density- Voltagema/cm volts 0 3.57 0.l 3.02 0.5 2.80 LO2.50 2.0 1.73 2.7 0.82 3.0 0

While other modifications of the invention and variations thereof whichmay be employed within the scope of the invention have not beendescribed, the invention is intended to include such as may be employedwithin the following claims:

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. A battery casing comprising an inner casing of a solid sodiumion-conductive material with one open end, an outer metallic casingcomprising an upper portion and a lower portion, the upper portion withopposite open ends, an inwardly extending flange affixed to the upperportion at its first open end, the lower portion with opposite openends, a removable closed end for its first open end. and an opening inthe removable closed end, the upper and lower portions joined togetherat their associated second open ends, the outer metallic casingsurrounding the inner casing with the exterior surface of the flange ona lower plane than the surface of the open end of the inner casing andspaced from the inner casing, a cap with a flange positioned adjacentthe flange of the upper portion of the outer metallic casing, and asingle low temperature melting glass seal sealing together the flange ofthe upper portion of the outer metallic casing and the cap flange andsealing the flanges to the outer wall of the inner casing adjacent itsopen end.

2. A battery casing as in claim 1, in which the cap flange extendsinwardly.

* i l i

1. A BATTERY CASING COMPRISING AN INNER CASING OF A SOLID SODIUMION-CONDUCTIVE MATERIAL WITH ONE OPEN END, AN OUTER METALLIC CASINGCOMPRISING AN UPPER PORTION AND A LOWER PORTION, THE UPPER PORTION WITHOPPOSITE OPEN ENDS, AN INWARDLY EXTENDING FLANGE AFFIXED TO THE UPPERPORTION AT ITS FIRST OPEN END, THE LOWER PORTION WITH OPPOSITE OPENENDS, A REMOVABLE CLOSED END FOR ITS FIRST OPEN END, AND AN OPENING INTHE REMOVABLE CLOSED END, THE UPPER AND LOWER PORTIONS JOINED TOGETHERAT THEIR ASSOCIATED SECOND OPEN ENDS, THE OUTER METALLIC CASINGSURROUNDING THE INNER CASING WITH THE EXTERIOR SURFACE OF THE FLANGE ONA LOWER PLANE THAN THE SURFACE OF THE OPEN END OF THE INNER CASING ANDSOACED FROM THE INNER CASING, A CAP WITH A FLANGE POSITIONED ADJACENTTHE FLANGE OF THE UPPER PORTION OF THE OUTER METALLIC CASING, AND ASINGLE LOW TEMPERATUR MELTING GLASS SEAL SEALING TOGETHER THE FLANGE OFTHE UPPER PORTION OF THE OUTER METALLIC CASING AND THE CAP FLANGE ANDSEALING THE FLANGES TO THE OUTER WALL OF THEINNER CASING ADJACENT ITSOPEN END.
 2. A battery casing as in claim 1, in which the cap flangeextends inwardly.